Anyone tried IMR4007 SSC with heavy bullets in 308?

[Keith Glasscock]

I'm looking for any information on this powder with heavy bullets in 308. Specifically, I need general load densities and velocities (barrel length).

Also, I need opinions about temperature stability.

I'm looking to develop a better 1k load than what I have. I really like the 208 Amax, but I could use a little more oomph to make 1k without going transonic. Right now, I'm calculating mach 1.12 at 1000 yards - still above mach 1, but quite transonic.

Thanks!

 

[Keith Glasscock]

If anyone is playing with QL, the brass I'm using is Winchester with a H2O capacity of 58.0 grains. The bullet seating is to an OAL of 2.960 with 208's

 

[TonyR]

If anyone is playing with QL, the brass I'm using is Winchester with a H2O capacity of 58.0 grains. The bullet seating is to an OAL of 2.960 with 208's

Here are some QL comparisons for a maximum powder charger of 46.9 grains with that setup. The usual cautions apply. Start 10% low and work up in 0.3 grain increments watching for pressure signs:

30 inch barrel==2613 fps
28 inch barrel==2581 fps
26 inch barrel==2546 fps

According to QL, there are other powders that will give you up to 90 fps more velocity at each barrel length.

FWIW, I tried 4007SSC in my 6mmBR and it gave me excellent ES/SD and vertical dispersion but was similarly short on velocity and struck me as very dirty stuff given the black soot left in the barrel. I didn't pursue it. I stopped at 26 inch barrel in QL because only about 98.6% of the powder is burned at that length. Hope this helps.

 

[Keith Glasscock]

Tony,

I'm open for other ideas (re-17 and N550 are obvious but seemingly limited) What other powders are you seeing work?

Thanks

 

[TonyR]

Tony,

I'm open for other ideas (re-17 and N550 are obvious but seemingly limited) What other powders are you seeing work?

Thanks

Staying with powders that burn 100% in a 26 inch barrel, RL-17 is the velocity king but RamShot Big Game and IMR4895 are close. The next group down includes RL-15, Norma 203B, H BL-C2, H380, and VV N550. Any of these worth a closer look?

 

[Keith Glasscock]

IMR-4895 sounds interesting. I can get that locally for a test.

 

[TonyR]

IMR-4895 sounds interesting. I can get that locally for a test.

Start of with something like 40.0 grains of IMR-4895 and work up in .3 grain steps. Quickload says the max pressure begins at 44.4 grains so be careful. If you can get that high, QL predicts 2583 fps from a 26 inch barrel and 2653 fps with a 30 inch barrel, again at the maximum rated pressure for the case which is 60191 psi. QL is predicting 2435 fps from a 30 inch barrel and a 40.0 grain load. That should give you something to compare with the results in your gun. Let us know how it works out.

 

[Keith Glasscock]

Thanks again Tony,

I'll be working on that right after the next big match (end of May). That way, I can get a baseline of performance before changing things up.